At present, in a backbone system application including the Enterprise Resource Planning (ERP) as a main application, it becomes a mainstream to integrate applications for each business purpose to operate them as one system. However, for several years, the increase of the cost by the increase of the number of servers has become a big problem in the customer. This is caused by reinforcing the capability of a server that executes a specific application or increasing the number of servers, when the processing amount increases for the specific application, because the server is prepared for each application, although plural applications are operated as one system. However, because all servers in the system do not usually use their full capabilities, the effective utilization of the idle resources is needed. Therefore, there is movement to adopt a mechanism that the operating state of the system is monitored to allocate the hardware resource dynamically and autonomously.
Incidentally, JP-A-2003-281293 discloses a method of charging for a data storage service. Specifically, a data volume converting means converts a volume of data of a user, which is stored in a storage, into a certain intermediate unit, and a use status monitoring means measures the volume of data in the storage at certain time intervals, records it into a residence information table, and records a file name and a storage path name of the data into a file information table. The charging processing means carries out a charging processing for each user on the basis of the residence information and the file information, and records the result into a user charging management information table. Then, a charging information providing means provides the charging information to the user. However, the system usage status of the application, which handles a little amount of data, cannot be accurately grasped based on the data amount.
As described above, when a mechanism in which the operating status of the system is monitored to allocate the hardware resource dynamically and autonomously is adopted, the system usage status by the user cannot be accurately grasped only by grasping the server-based usage status, that is, accumulating access time by each user for each server.